Cable comprising a fire-resistant layer

Abstract

A cable including at least one elongated conductive element and at least one fire-resistant insulating layer in direct physical contact with the elongated electrically conductive element, the fire-resistant layer is obtained by heat treatment of a liquid inorganic composition.

What is claimed is: 
     
         1 . Cable comprising:
 at least one elongated electrically conductive element; and   at least one fire-resistant layer surrounding said elongated electrically conductive element,   wherein said fire-resistant layer is in direct physical contact with said elongated electrically conductive element, and in that said fire-resistant layer is obtained by heat treatment of a liquid inorganic composition.   
     
     
         2 . Cable according to  claim 1 , wherein the fire-resistant layer is obtained by solidification of the liquid inorganic composition. 
     
     
         3 . Cable according to  claim 1 , wherein the heat treatment is performed at a temperature of at most 300° C. 
     
     
         4 . Cable according to  claim 1 , wherein the liquid inorganic composition comprises at least one transition metal oxide, at least one aluminosilicate and at least one solvent. 
     
     
         5 . Cable according to  claim 4 , wherein the liquid inorganic composition comprises at least 10% by weight of at least one transition metal oxide relative to the total weight of said composition. 
     
     
         6 . Cable according to  claim 4 , wherein the transition metal oxide is zirconium oxide. 
     
     
         7 . Cable according to  claim 4 , wherein the liquid inorganic composition comprises at least 2% by weight of at least one aluminosilicate relative to the total weight of said composition. 
     
     
         8 . Cable according to  claim 4 , wherein the liquid inorganic composition comprises at least 10% by weight of at least one solvent relative to the total weight of said composition. 
     
     
         9 . Cable according to  claim 8 , wherein the solvent is water. 
     
     
         10 . Cable according to  claim 4 , wherein the liquid inorganic composition also comprises at least one other silicate different from said aluminosilicate. 
     
     
         11 . Cable according to  claim 4 , wherein the liquid inorganic composition also comprises at least one plasticizer. 
     
     
         12 . Cable according to  claim 1 , wherein the liquid inorganic composition has a viscosity ranging from 10 −3  to 2×10 −3  m 2 /s (1000 to 2000 centistokes), said viscosity being measured at a temperature of 25° C., using a No. 4 Ford viscosity cup, according to the standard ASTM D1200. 
     
     
         13 . Cable according to  claim 1 , wherein the fire-resistant layer comprises at least one transition metal oxide and at least one aluminosilicate. 
     
     
         14 . Cable according to  claim 1 , wherein the thickness of said fire-resistant layer ranges from 20 to 500 μm. 
     
     
         15 . Cable according to  claim 1 , wherein the elongated conductive element is made of copper, aluminium, a copper alloy or an aluminium alloy. 
     
     
         16 . Cable according to  claim 1 , wherein said cable further comprises a plurality of elongated electrically conductive elements, each of the elongated electrically conductive elements being individually surrounded with at least one fire-resistant layer, and in that each of said fire-resistant layers is in direct physical contact with each of said elongated electrically conductive elements. 
     
     
         17 . Cable according to  claim 1 , wherein said cable also comprises at least one polymer layer ( 4 ) surrounding said fire-resistant layer. 
     
     
         18 . Process for preparing a cable as defined in  claim 1 , wherein said method comprises at least:
 i) a step of applying a liquid inorganic composition to the surface of at least one elongated electrically conductive element of said cable, and   ii) a step of heat treatment of said liquid inorganic composition to form said fire-resistant layer.   
     
     
         19 . Process according to  claim 18 , wherein steps i) and ii) are repeated several times.